Retinol is an important nutritive requirement of the corneal epithelium, and recently Ubels et al. (1984; 1986; 1987) determined that the lacrimal gland stores vitamin A as retinyl esters, and secretes retinol in the tear fluid. This finding is important and stimulates new interest in the lacrimal gland regarding retinoid metabolism. Our project is designed to begin to investigate retinoid delivery, uptake and storage by the lacrimal gland. We assume that retinol storage and handling by this tissue is similar to that of the retina. Based on this assumption, the specific aims of this research project are 1) to locate SRBP receptors in lacrimal gland tissue and 2) to investigate uptake and storage of retinol by lacrimal gland cells. To locate SRBP receptors we will incubate lacrimal gland pieces with FITC conjugated serum retinol binding protein (SRBP) bound to all-trans retinol. The tissue will be fixed, embedded, sectioned and examined by epifluorescence for the presence of FITC-SRBP on basal membranes of lacrimal gland cells. Alternative methods are presented if in vitro incubation of lacrimal gland pieces with FITC-SRBP/retinol is unsuccessful. Uptake and storage will be examined using lacrimal gland pieces incubated in the presence of SRBP/3H-all-trans retinol. After incubation for varying lengths of time in the presence of SRBP/3H-retinol, sampes of tissue are subjected to rapid freezing followed by freeze drying. The tissue is osmicated with vapors, embedded in Spurr resin, and processed for light and electron microscope autoradiography. The tissue is observed for the distribution of silver grains over lacrimal gland cells and subcellular components. These experiments should provide valuable information regarding retinol metabolism by the lacrimal gland and serve as the basis for expanded research in this area.